WASHINGTON -- The Supreme Court struck down a key section of a landmark voting rights law on Tuesday, saying Congress failed to take account of changing circumstances in the South when it decided which states would be subjected to additional scrutiny under the 1965 Voting Rights Act.

The court's 5-4 ruling in the case from Alabama frees states and municipalities with a history of racial discrimination from having to clear changes in voting procedures with the federal government -- at least for now. That restriction, part of the Voting Rights Act, has applied to nine states and parts of six others, mostly in the South.

Chief Justice John Roberts wrote the 5-4 decision in Shelby County v. Holder for the court's conservative majority. The four more liberal justices dissented.

The decision came in one of two major cases involving race to come before the high court this term. In the other, decided Monday, the court reaffirmed that affirmative action is constitutional but instructed lower-court judges to look far more critically at whether schools can prove their use of racial preferences is the only way to achieve a diverse student body.

Tuesday's opinion did not invalidate the Voting Rights Act's "preclearance" requirement outright. Instead, Roberts said Congress failed to update the formula it used to determine which states and counties would be covered by that requirement to take account of changing circumstances in the South. That failure, Roberts wrote, left the court "with no choice" but to declare Congress' formula unconstitutional.

Still, Roberts wrote, "our decision in no way affects the permanent, nationwide ban on racial discrimination in voting." He said "Congress may draft another formula based on current conditions."

The Voting Rights Act was passed by Congress and signed by President Lyndon Johnson -- with the Rev. Martin Luther King Jr. standing near -- in the wake of the violence and bloodshed that marked the 1950s and 1960s throughout the South.

It outlawed the types of voting practices that were common in many states, such as poll taxes and literacy tests, and set up legal and regulatory processes to overturn them.

The steel spine of the law was Section 5, which required certain states and municipalities to get federal permission before making changes in voting practices.

Under a formula devised to capture those states, Alabama, Georgia, Louisiana, Mississippi, South Carolina, Texas and Virginia, along with Arizona and Alaska, emerged with what they now consider a scarlet letter. The law was reauthorized in 1970, 1975, 1982 and 2006 with only minor changes.

But the Supreme Court's majority finally lost patience with lawmakers who had refused to update the list of states and municipalities deemed discriminatory, despite wholesale gains in the South by blacks and other minority voters and elected officials.

The ruling tosses the ball back to Congress, which could try to update a coverage formula based on 1972 data. Few observers, however, expect lawmakers to pick and choose among states and municipalities, even if they could overcome political inertia.

The court's conservatives, led by Roberts, had signaled their intentions during oral arguments in February. They expressed disdain for a geographic formula last updated in 1972 that forces most of the Deep South -- but also certain municipalities from Florida to Alaska -- to check even the relocation of polling places with the Department of Justice.

Justice Anthony Kennedy, the court's perennial swing vote, likened the states' plight to being "under the trusteeship of the United States government." Justice Antonin Scalia drew gasps inside the courtroom when he referred disdainfully to "racial entitlements."

And Roberts had long ago signaled his impatience with laws that give minorities a leg up on whites. In a 2007 decision on public school integration, he famously declared: "The way to stop discrimination on the basis of race is to stop discriminating on the basis of race."

Roberts and the court had punted on the issue four years ago, ruling that a Texas water district  and any municipality, for that matter  could get out from under Section 5 by demonstrating 10 years of good behavior. More than 200 municipalities have done so since the law's inception.

Even then, however, Roberts had warned that "things have changed in the South" and the pre-clearance requirements and coverage formula "raise serious constitutional questions."

The new case came to the court with two lower court strikes against Shelby County's challenge. In the most recent decision, the U.S. Court of Appeals for the D.C. Circuit ruled last year that the coverage formula "is not perfect, but the fit was hardly perfect in 1965."

The Obama administration warned the court not to mess with Congress' legislative authority. "Invidious racial discrimination is the most pernicious form of governmental discrimination prohibited by the Constitution," the government's brief said. That puts Congress "at the zenith of its constitutional authority."

Civil rights advocates and the court's left-leaning justices noted that the provision was used as recently as last year to beat back photo ID laws, redistricting plans and restrictions on early voting. Without it, they said, states could resume discriminatory practices.

But opponents of the law argued that the types of state and local election laws that continue to draw fire today "exist to a greater degree outside those covered jurisdictions than they do inside the jurisdictions," said Edward Blum, director of the Project on Fair Representation, who helped initiate Shelby County's lawsuit.

Both sides agree that progress has been made: Black voter turnout topped white turnout in last year's presidential election and was strongest in some of the Southern states subjected to the strictest oversight under the Voting Rights Act.

Minorities also have been elected to local offices in record numbers, thanks to the creation of so-called "majority-minority" districts. In 1965, the 11 states of the Old Confederacy, stretching from Virginia to Texas, had a total of three black state legislators. By 2009, the number had grown to 321, or 18% of the total, according to the National Conference of State Legislatures.

But over the same period, Southern legislatures that were overwhelmingly Democratic in 1965 have turned Republican. Today, the GOP controls both houses of the legislatures in all 11 states.

In recent years, the number of objections by the Justice Department to states' voting changes has declined dramatically. In 1976, there were 64 objections, including 30 in Texas alone. In recent years, the number dropped to five or less. While there were 10 objections last year, this year has produced only one.

Meanwhile, the number of municipalities that have "bailed out" of Section 5 by maintaining a clean record on voting rights for 10 years has risen. From 1998 to 2008, only Virginia municipalities were excused from federal oversight. In the last three years, they were joined by several in California, Texas, Alabama, and the entire state of New Hampshire.

The law's defenders say Section 5 prevented Texas, Florida and South Carolina from enacting new voting restrictions in 2012. This year, they say, it stands as a bulwark against similar discrimination. In Beaumont, Texas, a school board election was canceled to prevent white candidates from running unopposed in three majority-black districts. In North Carolina, lawmakers have proposed new restrictions on voter identification, registration and early voting.

The remainder of the Voting Rights Act wasn't challenged in the case. The law still will provide for legal challenges to voting changes deemed discriminatory in any state. But those after-the-fact challenges can be costly and time-consuming.

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WASHINGTON (AP) - The Supreme Court says a key provision of the landmark Voting Rights Act cannot be enforced until Congress comes up with a new way of determining which states and localities require close federal monitoring of elections.

The justices said in 5-4 ruling Tuesday that the law Congress most recently renewed in 2006 relies on 40-year-old data that doesn't reflect racial progress and changes in U.S. society.

The court did not strike down the advance approval requirement of the law that has been used, mainly in the South, to open up polling places to minority voters in the nearly half century since it was first enacted in 1965. But they said lawmakers must update the formula for determining which parts of the country must seek Washington's approval for election changes.